1. Field
One or more embodiments of the present invention relate to a battery pack.
2. Description of Related Art
As the development and demand of mobile devices have recently been increased, demands on secondary batteries as energy sources have been rapidly increased. Among these secondary batteries, many studies for lithium secondary batteries have been conducted. Currently, lithium secondary batteries are commercialized and widely used.
Battery packs are generally classified into a hard battery pack and an inner battery pack based on how the secondary battery is mounted to a case. Since the hard battery pack forms a part of the external shape of an electronic device on which it is mounted, it is easy to mount the hard battery pack on the electronic device in its use. However, since a case is necessarily designed suitable for the kind of the electronic device in the state that a bare cell is mounted in the hard pack, the hard pack is relatively high priced, and the compatibility of the hard pack is low.
On the other hand, since the inner pack is mounted in the electronic device and then covered by a cover that forms a part of the electronic device, its mounting is relatively complicated. However, the inner pack is easily designed and inexpensive, and the compatibility of the inner pack is high.
In general, an inner battery pack includes a chargeable/dischargeable bare cell; a protection circuit module electrically connected to the bare cell to control the charge/discharge of the bare cell; a resin filled in the gap between the bare cell and the protection circuit module; and an outer frame molded in a shape attachable to an electronic device by packing the bare cell, the protection module and the resin therein.
In order to manufacture and assemble such a battery pack, a lead is connected to a positive electrode, and a positive temperature coefficient (PTC) thermistor is connected to a negative electrode. In this state, the protection circuit module is electrically connected to the lead and the PTC thermistor. Subsequently, a protection circuit module and a bare cell are mechanically fixed to each other by filling a resin into the gap between the protection circuit module and the bare cell so that the protection circuit module is not separated from the bare cell. Then, the bare cell and the protection circuit module, formed in a single body, are packed using an outer frame having a shape attachable to an electronic device. Here, the outer frame is integrally formed with the bare cell, the protection circuit module and the resin by molding them with another resin.
Subsequently, the battery pack may inserted into the electronic device to supply power to the electronic device. However, over time a gap may be produced between the battery pack and the electronic device, and therefore, the battery pack may be easily separated or dislodged from the electronic device. Further, when the battery pack is reversely inserted into the electronic device, malfunction may occur or the electronic device may not operate.